Rep. Henry Cuellar, D-Texas, said Wednesday that a “virtual border” would be more effective than the wall that President-elect Donald Trump wants to build on the U.S.-Mexico border.

Cuellar made the statement near Rio Grande City, Texas, where the Department of Homeland Security has placed military hand-down aerostat surveillance balloons, San Antonio TV station KENS5 reported.

“We can’t come in with the new administration and have a very simplistic view that you have a 14th century solution to a 21st century problem,” said Cuellar, who represents a district that runs along the Texas-Mexico border.

Cuellar said tools like the balloons, sensors and watch towers would be cheaper and more effective than a physical wall like the one President-elect Donald Trump has proposed.

“You can’t say ‘Put a wall’ and that solves all the problems, because we’re playing defense on the 1-yard line,” he said.

Cuellar said more modern methods would cost about $1 million per mile along the border.

“You put one mile of fencing, with construction and maintenance, it would be about $6.5 million,” he said.

Trump’s transition team has already reached out to Border Patrol sectors asking where to best erect a physical barrier, Cuellar said.

“The request has been made already: ‘Tell us where you think we ought to have more fencing.’”